U.S. patent application number 14/150766 was filed with the patent office on 2014-07-17 for rotating electrical machine.
This patent application is currently assigned to ASMO CO., LTD.. The applicant listed for this patent is ASMO CO., LTD.. Invention is credited to Tsuyoshi KINOSHITA, Takeo NODA.
Application Number | 20140197708 14/150766 |
Document ID | / |
Family ID | 51164630 |
Filed Date | 2014-07-17 |
United States Patent
Application |
20140197708 |
Kind Code |
A1 |
NODA; Takeo ; et
al. |
July 17, 2014 |
ROTATING ELECTRICAL MACHINE
Abstract
A rotating electrical machine comprising an armature; a yoke;
and a plurality of magnets arrayed in a ring shape along an inner
peripheral face of the yoke. The magnets are respectively formed in
circular arc shapes fit with the inner peripheral face of the yoke,
and are fixed to the yoke. The magnets are arrayed along the
circumferential direction of the yoke with gaps between each other,
a central portion in a circumferential direction of each of the
magnets is disposed so as to be opposed in a yoke diameter
direction to the gap between other magnets arrayed adjacent to each
other, a boundary portion between a pair of magnetic poles in each
of the magnets is positioned at central position in the
circumferential direction of each of the magnets, and each of the
magnets is formed thicker at end portions than at the central
portion in the circumferential direction thereof.
Inventors: |
NODA; Takeo;
(Hamamatsu-city, JP) ; KINOSHITA; Tsuyoshi;
(Hamamatsu-city, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
ASMO CO., LTD. |
Kosai-city |
|
JP |
|
|
Assignee: |
ASMO CO., LTD.
Kosai-city
JP
|
Family ID: |
51164630 |
Appl. No.: |
14/150766 |
Filed: |
January 9, 2014 |
Current U.S.
Class: |
310/156.38 |
Current CPC
Class: |
H02K 1/2786 20130101;
H02K 29/03 20130101 |
Class at
Publication: |
310/156.38 |
International
Class: |
H02K 1/27 20060101
H02K001/27 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 11, 2013 |
JP |
2013-003720 |
Claims
1. A rotating electrical machine comprising: an armature; a yoke
that is formed in a circular cylindrical shape and that is provided
at outer side in a radial direction of the armature; and a
plurality of magnets that are arrayed in a ring shape along an
inner peripheral face of the yoke, that are respectively formed in
circular arc shapes that are fit with the inner peripheral face of
the yoke, and that are fixed to the inner peripheral face of the
yoke; wherein: the plural magnets are arrayed along the
circumferential direction of the yoke with gaps between each other,
a central portion in a circumferential direction of each of the
magnets is disposed so as to be opposed in a yoke diameter
direction to the gap between other magnets arrayed adjacent to each
other, a boundary portion between a pair of magnetic poles in each
of the magnets is positioned at central position in the
circumferential direction of each of the magnets, and each of the
magnets is formed thicker at end portions in the circumferential
direction thereof than at the central portion in the
circumferential direction thereof.
2. The rotating electrical machine of claim 1, wherein: the magnets
are formed thicker at the circumferential direction end portions
than at the circumferential direction central portion by forming a
flat face to a circumferential direction central portion of an
outer peripheral portion of each of the magnets so as to extend
along a direction parallel to a tangential direction to the
yoke.
3. The rotating electrical machine of claim 1, wherein: the magnets
are formed thicker at the circumferential direction end portions
than at the circumferential direction central portion by setting a
curvature of an inner peripheral portion of the magnets larger than
a curvature of an outer peripheral portion of the magnets.
4. The rotating electrical machine of claim 1, wherein: the magnets
are formed thicker at the circumferential direction end portions
than at the circumferential direction central portion by forming a
flat face to a circumferential direction central portion of an
outer peripheral portion of each of the magnets so as to extend
along a direction parallel to a tangential direction to the yoke
and by setting a curvature of an inner peripheral portion of the
magnets larger than a curvature of an outer peripheral portion of
the magnets.
5. The rotating electrical machine of claim 1, wherein the number
of the plurality of magnets is an odd number.
6. The rotating electrical machine of claim 1, wherein the number
of poles of the plurality of magnets is ten poles, and the number
of slots of the armature is twelve.
7. The rotating electrical machine of claim 1, wherein the number
of poles of the plurality of magnets is six poles, and the number
of slots of the armature is eighteen.
8. The rotating electrical machine of claim 1, wherein the number
of poles of the plurality of magnets is fourteen poles, and the
number of slots of the armature is twelve.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is claims priority under 35 USC 119 from
Japanese Patent Application, No. 2013-003720 filed Jan. 11, 2013,
the disclosure of which is incorporated by reference herein.
BACKGROUND OF THE INVENTION
[0002] 1. Technical Field
[0003] The present invention relates to a rotating electrical
machine.
[0004] 2. Related Art
[0005] In existing technology, as illustrated for example in
Japanese Patent Application Laid-Open (JP-A) No. 2012-120306, a
known rotating electrical machine is provided with an armature, a
yoke that houses the armature, and plural magnets that are disposed
in a ring shape around the inner peripheral face of the yoke. In
such a rotating electrical machine, the plural magnets are
respectively formed in circular arc shape which fits with the inner
peripheral surface of the yoke, and attached to the inner
peripheral surface of the yoke. Moreover, generally in each of the
magnets, the pair of magnetic poles is aligned in a row along the
circumference of the yoke, with the boundary portion of the pair of
magnetic poles set at the circumferential direction central portion
of the magnet.
[0006] The plural magnets are arrayed along the yoke
circumferential direction with gaps between each other, with a
circumferential direction central portion of one magnet (a portion
on the circumferential direction center side) disposed so as to be
opposed in the yoke diameter direction to a gap between other
adjacent magnets. Moreover, a boundary of a pair of magnetic poles
in the magnets is positioned at a circumferential direction central
position (center) of each of the magnets, with the magnets formed
with a constant thickness spanning along their entire
circumferential direction lengths.
SUMMARY
[0007] However, in the above rotating electrical machine, the
circumferential direction central portion of each of the magnets is
disposed so as to be opposed in the yoke diameter direction to a
gap between other adjacent magnets, and the magnets are formed with
a uniform thickness spanning along their entire circumferential
direction lengths. Thus during operation of the rotating electrical
machine, with respect to the armature, differences arises in the
surface magnetic flux density between when the magnetic poles
switch at the circumferential direction central portion of the
magnets and when the magnetic poles switch at the circumferential
direction end portions of the magnets. There is accordingly a
concern regarding exciting force generated that may cause noise
accompanying the differences between these surface magnetic flux
densities.
[0008] In consideration of the above issue, the present invention
provides a rotating electrical machine capable of reducing exciting
force.
[0009] In order to address the above issue, a rotating electrical
machine of the first exemplary embodiment of the present invention
includes: an armature; a yoke that is formed in a circular
cylindrical shape and that is provided at a radial direction outer
side of the armature; plural magnets that are arrayed in a ring
shape along an inner peripheral face of the yoke, that are
respectively formed in circular arc shapes that fit with the inner
peripheral face of the yoke, and that are fixed to the inner
peripheral face of the yoke. The plural magnets are arrayed along
the circumferential direction of the yoke with gaps between each
other, a central portion in a circumferential direction of each of
the magnets is disposed so as to be opposed in the yoke diameter
direction to the gap between other magnets arrayed adjacent to each
other, a boundary portion between a pair of magnetic poles in each
of the magnets is positioned at a central position in the
circumferential direction of each of the magnets, and each of the
magnets is formed thicker at its circumferential direction end
portions than at its circumferential direction central portion.
[0010] According to such a rotating electrical machine, each of the
magnets is formed thicker at the circumferential direction end
portions than at the circumferential direction central portion.
Consequently, during operation of the rotating electrical machine,
with respect to the armature, a difference in surface magnetic flux
density can be suppressed from occurring between when the magnetic
poles switch at the circumferential direction central portion of
the magnets and when the magnetic poles switch at the
circumferential direction end portions of the magnets. This thereby
enables generation of exciting force that may cause noise to be
suppressed.
[0011] A rotating electrical machine of a second aspect of the
present invention is the rotating electrical machine of the first
aspect, wherein: the magnets are formed thicker at the
circumferential direction end portions than at the circumferential
direction central portion by forming a flat face to a
circumferential direction central portion of an outer peripheral
portion of each of the magnets so as to extend along a direction
parallel to a tangential direction to the yoke.
[0012] According to this rotating electrical machine, the
circumferential direction end portions can be made thicker than the
circumferential direction central portions of the magnets by using
a simple configuration in which the flat faces are formed to
circumferential direction central portions of the outer peripheral
portions of the magnets so as to extend along a direction parallel
to a tangential direction to the yoke.
[0013] A rotating electrical machine of a third aspect of the
present invention is the rotating electrical machine of the first
aspect, wherein: the magnets are formed thicker at the
circumferential direction end portions than at the circumferential
direction central portion by setting a curvature of an inner
peripheral portion of the magnets larger than a curvature of an
outer peripheral portion of the magnets.
[0014] According to this rotating electrical machine, the
circumferential direction end portions can be made thicker than the
circumferential direction central portions of the magnets by using
a simple configuration in which the curvature of the inner
peripheral portion of the magnets is set larger than the curvature
of the outer peripheral portion of the magnets.
[0015] A rotating electrical machine of a fourth aspect of the
present invention is the rotating electrical machine of the first
aspect, wherein: the magnets are formed thicker at the
circumferential direction end portions than at the circumferential
direction central portion by forming a flat face to a
circumferential direction central portion of an outer peripheral
portion of each of the magnets so as to extend along a direction
parallel to a tangential direction to the yoke and by setting a
curvature of an inner peripheral portion of the magnets larger than
a curvature of an outer peripheral portion of the magnets.
[0016] According to this rotating electrical machine, the
circumferential direction end portions can be made thicker than the
circumferential direction central portions of the magnets by using
a simple configuration in which the flat faces are formed to
circumferential direction central portions of the outer peripheral
portions of the magnets so as to extend along a direction parallel
to a tangential direction to the yoke, and the curvature of the
inner peripheral portion of the magnets is set larger than the
curvature of the outer peripheral portion of the magnets.
[0017] Note that, as in a fifth aspect of the present invention,
the number of the plural magnets may be an odd number.
[0018] Moreover, as in a sixth aspect of the present invention, the
number of poles of the plural magnets may be ten poles, and the
number of slots of the armature may be twelve.
[0019] Moreover, as in a seventh aspect of the present invention,
the number of poles of the plural magnets may be six poles, and the
number of slots of the armature may be eighteen.
[0020] Moreover, as in an eighth aspect of the present invention,
the number of poles of the plurality of magnets may be fourteen
poles, and the number of slots of the armature may be twelve.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] Embodiments of the present invention will be described in
detail based on the following figures, wherein:
[0022] FIG. 1 is a plan view along an axial direction of a rotating
electrical machine according to a first exemplary embodiment of the
present invention;
[0023] FIG. 2 is a plan view of a magnet of the first exemplary
embodiment of the present invention;
[0024] FIG. 3 is graph illustrating measurement results of surface
magnetic flux density against rotation angle for the magnet
illustrated in FIG. 2;
[0025] FIG. 4 is a plan view of a magnet in a second exemplary
embodiment of the present invention;
[0026] FIG. 5 is a plan view of a magnet in a third exemplary
embodiment of the present invention;
[0027] FIG. 6 is a plan view of a rotating electrical machine
according to a first modified example;
[0028] FIG. 7 is a plan view of a rotating electrical machine
according to a second modified example;
[0029] FIG. 8 is a graph illustrating measurement results of
surface magnetic flux density against rotation angle for magnets of
comparative example; and
[0030] FIG. 9 is a diagram illustrating the N pole waveform and the
S pole waveform of FIG. 8 superimposed on each other.
DETAILED DESCRIPTION OF THE INVENTION
First Exemplary Embodiment
[0031] Explanation first follows regarding a first exemplary
embodiment of the present invention.
[0032] A rotating electrical machine 10 according to the first
exemplary embodiment of the present invention illustrated in FIG. 1
is, for example, a brushless motor. The rotating electrical machine
10 is equipped with a stator 12 that serves as an armature, and a
rotor 14.
[0033] The stator 12 includes a stator core 16. The stator core 16
includes plural teeth 18 that extend in a substantially radial
direction centered on a central portion of the rotating electrical
machine 10. Stator coils are wound on the teeth 18.
[0034] The rotor 14 is rotated by a rotating magnetic field formed
by the stator 12. The rotor 14 includes a yoke 20 and plural
magnets 22. The yoke 20 is formed in a circular cylindrical shape,
and is provided at the radial direction outer side of the stator
12.
[0035] The plural magnets 22 are arrayed in a ring shape along an
inner peripheral face 20A of the yoke 20. The plural magnets 22 are
formed in a circular arc shape which fits with the inner peripheral
face 20A of the yoke 20, and are fixed to the inner peripheral face
20A of the yoke 20.
[0036] A flat face 24 is formed at a central portion in a
circumferential direction of an outer peripheral portion 22A of
each of the magnets 22 so as to extend along a direction parallel
to a tangential direction of the yoke 20. The flat face 24 is
formed spanning along an entire length of a longitudinal direction
of the magnets 22, this being the same direction as the axial
direction of the yoke 20. Due to forming the flat face 24, each of
the magnets 22 is formed with end portions 28 in the
circumferential direction that are thicker than the central portion
26 in the circumferential direction (see FIG. 2).
[0037] The circumferential direction of the magnets 22 is a
direction along the circumferential direction of the yoke 20. The
circumferential direction central portion 26 of each of the magnets
22 is a portion at the circumferential direction center side of the
magnets 22, and the circumferential direction end portions 28 of
each of the magnets 22 are portions at the circumferential
direction end sides of each of the magnets 22. Each of the magnets
22 includes a pair of magnetic poles 23A, 23B (N pole, S pole) in a
row along the circumferential direction of the yoke 20. A boundary
portion 23C of the pair of magnetic poles 23A, 23B is positioned at
a circumferential direction central position (center) of each of
the magnets 22.
[0038] The plural magnets 22 are each of the same configuration as
each other. The plural magnets 22 are arrayed along the yoke 20
circumferential direction with equal gaps 30 between each other.
The circumferential direction central portion 26 of each given
magnet 22, formed with the flat face 24, is disposed so as to be
opposed in the yoke 20 diameter direction to the gap 30 between
other adjacent magnets 22.
[0039] In the first exemplary embodiment, the number of the plural
magnets 22 is five, as an example of an odd number. The number of
the poles of the plural magnets 22 is ten poles, and the number of
the slots 32 between the teeth 18 formed to the stator 12 is
twelve.
[0040] Explanation next follows regarding operation and
advantageous effects of the first exemplary embodiment of the
present invention.
[0041] FIG. 3 is a graph illustrating results of surface magnetic
flux density measurements against rotation angle regarding the
magnets 22 of the present exemplary embodiment. In contrast
thereto, FIG. 8 is a graph illustrating results of surface magnetic
flux density measurements against rotation angle regarding magnets
in Comparative Example. FIG. 9 is a diagram illustrating waveforms
of the N pole and waveforms of the S pole of FIG. 8, superimposed
on each other. Note that in contrast to the magnets 22 of the
present exemplary embodiment, magnets in Comparative Example are
formed with the thickness of their circumferential direction
central portion and the thickness of their circumferential
direction end portions the same as each other.
[0042] In other word, the magnets of the Comparative Example are
formed with a uniform thickness spanning along the entire length in
the circumferential direction, in contrast to the magnets 22 of the
present exemplary embodiment. In the Comparative Example, similarly
to in the present exemplary embodiment, plural magnets are arrayed
with gaps between each other in the yoke circumferential direction,
such that the circumferential direction central portion of one
magnet is disposed so as to be opposed in the yoke diameter
direction to a gap between other adjacent magnets. In the
Comparative Example the boundary portion between a pair of magnetic
poles in each of the magnets is also placed at a magnet
circumferential direction central position.
[0043] In a thus configured Comparative Example, the
circumferential direction central portion of the magnets are
opposed in the yoke diameter direction to respective gaps between
adjacent magnets, and the magnets are formed with a uniform
thickness along the entire length direction in the circumferential
direction. Thus, as illustrated in FIG. 8 and FIG. 9, during rotor
rotation, with respect to the stator, a difference in the surface
magnetic flux density arises between when the magnetic poles switch
at the circumferential direction central portion of the magnets and
when the magnetic poles switch at the circumferential direction end
portions of the magnets. There is accordingly concern that exciting
force that may cause noise is generated accompanying the difference
in surface magnetic flux density.
[0044] In contrast thereto, in the rotating electrical machine 10
according to the first exemplary embodiment of the present
invention, as illustrated in FIG. 2, each of the magnets 22 is
formed with the circumferential direction end portions 28 thicker
than the circumferential direction central portion 26. Thus, as
illustrated in FIG. 3, during rotor rotation, with respect to the
stator, difference in surface magnetic flux density between when
the magnetic poles switch at the magnet circumferential direction
central portion and the when magnetic poles switch at the magnet
circumferential direction end portions can be suppressed from
occurring. Generation of exciting force that may cause noise can
accordingly be suppressed. Note that, in the graphs of FIGS. 3, 8
and 9, values at rotation angles of 0 degree and 72 degrees
indicate surface magnetic flux densities when the magnetic poles
switch at the circumferential direction end portions of the magnets
and values at rotation angle of 36 degrees indicate surface
magnetic flux densities when the magnetic poles switch at the
circumferential direction central portion of the magnets. Further,
a line Sn indicates a wave shape of N pole and a line Ss indicates
a wave shape of S pole.
[0045] As illustrated in FIG. 2, the circumferential direction end
portions 28 can be made thicker than the circumferential direction
central portion 26 of the magnets 22 by using a simple
configuration in which the flat face 24 is formed to the outer
peripheral portion 22A at the circumferential direction central
portion of each of the magnets 22 so as to extend along a direction
parallel to a tangential direction of the yoke 20. An increase in
cost can accordingly be suppressed.
[0046] Note that in the first exemplary embodiment of the present
invention, the rotating electrical machine 10 is applied to a
brushless motor, however application may be made to a brushed
direct current motor equipped with an armature rotor, and a stator
including magnets and a yoke.
Second Exemplary Embodiment
[0047] Explanation follows regarding a second exemplary embodiment
of the present invention.
[0048] In the second exemplary embodiment of the present invention,
the configuration of magnets 222 is changed with respect to the
first exemplary embodiment in the following manner. Namely, in the
second exemplary embodiment illustrated in FIG. 4, a radius R1 of
an inner peripheral portion 222B of the magnets 222 is set shorter
than a radius R2 of the outer peripheral portion 222A of the
magnets 222. The respective centers O1, O2 with respect to the
radii R1, R2 are set so as to be positioned at different positions
on a hypothetical line L extending along the magnets 222 radial
direction and passing through a circumferential direction central
position (center) of the magnets 222. Because of this arrangement,
a curvature of the inner peripheral portion 222B of the magnets 222
becomes larger than a curvature of the outer peripheral portion
222A of the magnets 222.
[0049] Since the curvature of the inner peripheral portion 222B is
made larger than the curvature of the outer peripheral portion
222A, in the magnets 222, the circumferential direction end
portions 228 are formed thicker than the circumferential direction
central portion 226. The flat face 24 described above (see FIG. 2)
is omitted from the magnets 222 in the second exemplary
embodiment.
[0050] Note that configuration other than that described above in
the second exemplary embodiment is similar to that of the first
exemplary embodiment, the same reference numerals allocated
thereto, and explanation thereof omitted.
[0051] With such a configuration, similarly to in the above first
exemplary embodiment, during rotor rotation, with respect to the
stator, differences in surface magnetic flux density when magnetic
poles switch at the circumferential direction central portion 226
of the magnets 222, and when magnetic poles switch at the
circumferential direction end portions 228 of the magnets 222, can
be suppressed from occurring. Thus generation of exciting force
that may cause noise can be suppressed.
[0052] Moreover, the thickness of the circumferential direction end
portions 228 can be made thicker than the circumferential direction
central portion 226 of the magnets 222 by using a simple
configuration in which the curvature of the inner peripheral
portion 222B is made larger than the curvature of the outer
peripheral portion 222A in the magnets 222. An increase in cost can
accordingly be suppressed.
Third Exemplary Embodiment
[0053] Explanation next follows regarding a third exemplary
embodiment of the present invention.
[0054] In the third exemplary embodiment of the present invention,
the configuration of magnets 322 is changed from that of the first
exemplary embodiment described above in the following manner.
Namely, as illustrated in FIG. 5, in the third exemplary
embodiment, similarly to in the first exemplary embodiment, a flat
face 24 is formed at circumferential direction central portions of
an outer peripheral portion 322A of each of the magnets 322 so as
to extend along a direction parallel to a tangential direction of a
yoke 20. In the magnets 322, similarly to in the second exemplary
embodiment, a curvature of an inner peripheral portion 322B is made
larger than a curvature of the outer peripheral portion 322A.
[0055] In this manner, in the magnets 322 the thickness of the
circumferential direction end portions 328 is formed thicker than
the circumferential direction central portion 326 by both forming
the flat face 24 at the circumferential direction central portion
of the outer peripheral portion 322A of each of the magnets 322 so
as to extend along a direction parallel to the tangential direction
to the yoke 20, and setting the curvature of the inner peripheral
portion 322B is made larger than the curvature of the outer
peripheral portion 322A.
[0056] Note that in the third exemplary embodiment, configuration
other than that described above is similar to that of the first
exemplary embodiment and the second exemplary embodiment, the same
reference numerals are allocated thereto, and explanation is
omitted thereof.
[0057] In such a configuration too, similarly to in the first
exemplary embodiment and the second exemplary embodiment described
above, during rotor rotation, with respect to the stator, a
difference in surface magnetic flux density between when the
magnetic poles switch at the circumferential direction central
portion 326 of the magnets 322, and when the magnetic poles switch
at the circumferential direction end portions 328 of the magnets
322, can be suppressed from occurring. Consequently, generation of
exciting force that may cause noise can be suppressed.
[0058] Moreover, the thickness of the circumferential direction end
portions 328 of the magnets 322 can be made thicker than that of
the circumferential direction central portion 326 of the magnets
322 using a simple configuration in which the flat face 24 is
formed to the outer peripheral portion 322A at the circumferential
direction central portion of each of the magnets 322 so as to
extend along a direction parallel to the tangential direction of
the yoke 20, and the curvature of the inner peripheral portion 322B
is made larger than the curvature of the outer peripheral portion
322A in the magnets 322.
[0059] Note that the second exemplary embodiment and the third
exemplary embodiment of the present invention may also, similarly
to in the first exemplary embodiment, be applied to brushed direct
current motors.
[0060] Moreover, the number of the plural magnets 22 in the above
first to third exemplary embodiments is not limited as five.
[0061] In the above first to third exemplary embodiments, as for
example illustrated in FIG. 6, the number of the plural magnets 22
may be three, the number of the poles of the plural magnets may be
six, and the number of slots 32 between the teeth 18 formed to the
stator 12 may be eighteen. Moreover, as illustrated in FIG. 7, the
number of the plural magnets 22 may be seven, the number of the
poles of the plural magnets 22 may be fourteen, and the number of
slots 32 between the teeth 18 formed to the stator 12 may be
twelve. In the modified examples illustrated in FIG. 6 and FIG. 7,
configuration other than that described above is similar to the
first and the second exemplary embodiments, is allocated the same
reference numerals and further explanation thereof is omitted.
[0062] Examples of the present invention have been given above,
however the present invention is not limited to the above, and
obviously various modifications may be implemented without
departing from the scope of the invention.
* * * * *